Telephony, messaging and on-demand streaming services are examples for Point-to-Point (PTP) or unicast communication services. Broadcast and multicast services, on the other hand, are based on Point-to-Multipoint (PTM) communication. Using PTM communication, content (such as voice, text, graphics or multimedia data) is transmitted from typically a single source to multiple destinations. PTM services include for example streaming services or file delivery services.
A broadcast PTM service of a broadcast-enabled network, for example a mobile communication network, broadcasts content data into a predetermined geographical area, i.e. a broadcast service area. The users do not need to register or join a group prior to receiving the content.
A multicast PTM service delivers content to a group of users in a particular area, i.e. a multicast service area. Prior to receiving the content, the users have to subscribe to a particular multicast group, e.g. a Multicast Subscription Group. Usually, a multicast group includes a plurality of users interested in a particular content, for example news in the field of sports, economics, politics, etc.
The 3GPP (3rd-Generation Partnership Project) has specified broadcast and multicast services for GSM (Global System for Mobile Communications) and UMTS (Universal Mobile Telecommunication System) networks, namely the Multimedia Broadcast and Multicast Service (MBMS) feature. The feature is documented for example in the 3GPP TS (Technical Specification) 23.246 and in the TS 26.346. MBMS adds a plurality of broadcast/multicast-related techniques to conventional GSM or UMTS networks. For performing these techniques, a functional entity is specified that controls the broadcast multicast delivery of services, which is called the Broadcast/Multicast Service Center (BM-SC).
Within MBMS, the BM-SC is responsible for providing and delivering broadcast/multicast services originating from any kind of content provider (broadcast/multicast content source), for example a video clip distribution server, automotive warning server, news server, etc. The BM-SC serves as an entry point for content-delivery services, sets up and controls MBMS transport bearers, and can additionally be used to initiate MBMS transmissions. For example, the BM-SC may provide the service announcements that signal an upcoming multicast transmission to a User Equipment (UE) being member of the related group. These announcements include all necessary information such as multicast service identifier, Internet Protocol (IP) multicast addresses, time of transmission, and media descriptions that a UE needs to join a multicast session.
Each broadcast/multicast service is related to a service area (broadcast/multicast service area), which is the geographical area or zone within which the content can be broadcasted/multicasted or transmitted. The service area may comprise the whole PLMN (Public Land Mobile Network) of an MNO (Mobile Network Operator) or may even comprise several PLMNs, if agreed upon in a service level agreement. On the other hand, a service area may be configured to be as small as a single radio cell of a network or a plurality of radio cells. In general, a service area comprises a reasonable part of a PLMN.
Downstream of a PTM data source, each node in the network has a list of further downstream nodes to determine to which nodes it should forward MBMS content. Thus, a hierarchically organized content distribution is created with the base transceiver stations/Node B stations (e-Node B stations) serving a single radio cell each and thus forming the leaves of the distribution tree.
In many networks, the service area is allocated statically, i.e. the content is distributed to the same (fixed) destination area. For example, today's broadcast services (e.g. FM or AM broadcasts) are de-facto static. Some other, like MBMS, allow limited update capabilities for the service area allocation. In MBMS, a service area is configured individually for each multicast service, but the service area configured for this service is then not adjusted during transmission.
That is, in these existing broadcasting/multicasting solutions, it is not possible to modify the destination area for the content of the same broadcast/multicast service dynamically during a day. However, for each broadcast/multicast session, some services and applications of a broadcast/multicast service, like mobile TV, multimedia podcasting, localized news or automotive warning applications, may only be important for some of the recipients in a broadcast/multicast service area. Others may be of value for all of these recipients.